An estimated 3% of the world population has been infected with Hepatitis C virus (HCV). Greater than 80% of those infected individuals become chronically infected, putting them at risk for liver cirrhosis and liver cancer. To date there is no approved vaccine, and interferon the only approved treatment, resolves only 20% of those treated. HCV does not grow well in tissue culture and heterologous expression of the structural proteins in a variety of systems have met with only moderate success. The limited quantity of purified HCV polypeptides has hindered investigations into understanding the host immune response, virus biology, as well as, the development of vaccines and therapeutics. This Phase I research will test the feasibility of utilizing a unique eukaryotic heterologous system to efficiently express and secrete recombinant viral structural proteins that have native conformation. Use of this system for expression has the potential to produce large quantities of high quality protein for a variety of uses including the development of a safe, efficacious and cost effective vaccine. PROPOSED COMMERCIAL APPLICATIONS: More than 500 million people world-wide are chronically infected with Hepatitis C virus; there is no vaccine, and therapies are limited. The proposed research will express the HCV structural proteins, and assess the quantity and quality of the recombinant protein. Successful expression of high levels of conformationally relevant protein could contribute to the development of a safe, efficacious and cost effective HCV vaccine.